Which of the following is commonly used to measure sludge volume?

The method commonly used to measure sludge volume is the sedimentation method. This approach involves allowing sludge to settle in a container over a specific period, allowing for the measurement of the volume of sludge that settles at the bottom of the container. The volume of settled sludge can then be used to gauge the concentration and characteristics of the sludge.

While options like electrical conductivity and ultrasonic measurement are used for other purposes related to water treatment and analysis, they are not standard techniques for measuring sludge volume. The bottling method, although it involves collecting samples, does not provide a direct measurement of volume specific to sludge. Thus, the sedimentation method is a fundamental practice in environmental compliance for accurately assessing sludge volumes in wastewater treatment facilities.